If you are seeing weird colors or washed out colors when trying to watch content on your Roku device, the problem stems from your display or projector not fully supporting DOLBY VISION, which is turned on my default in Roku.
The Roku device is SUPPOSED TO automatically detect whether or not your display can support video formats such as HDR, HDR+ HDR10 and Dolby Vision. Dolby Vision is a color and contrast correction protocol that is broadcasted over the HDMI signal. If it's turned on (automatically in Roku) and the display your are using doesn't (fully) support Dolby Vision, then you will get these weird, washed out, greenish, purplish, pink colors.
THE SOLUTION IS, to go into settings, then go into the display settings, and change the display type to either 1080p, or 4K without Dolby Vision.